foetal growth Flashcards
Best way to check pregnancy stage
Symphysis Fundal Height (SPH). identifies the distance between the pubic symphysis and the top of the uterus
What can cause increased or decreased SPH
Values that are lower than they should may result from: wrong last menstrual period date, the baby in a transverse lie, or complications including oligohydramnios (low levels of amniotic fluid) or a baby that is small for gestational age (SGA).
Higher values may also be found, due to: wrong last menstrual period date, multiple pregnancy, or maternal obesity.
Complications could include molar pregnancy, fibroids, polyhydramnios or a baby that is large for gestational age (LGA).
What two components contribute to foetal size
Genetic and substrate availability
What are the four parameters to determine foetal growth
Biparietal diameter (BPD), Head Circumference (HC), Abdominal Circumference (AC) and Femur Length (FL). They are combined to give the Estimated Fetal Weight (EFW).
What is the rate of growth at 15 weeks, 20 weeks, 34 weeks and after 34 weeks
14-15 wks: 5g /day
20 wks: 10 g/day
32-34 wks: 30-35g/day
> 34 wks: growth rate decreases
Three phases of foetal growth
Cellular hyperplasia (increased cell numbers): 4-20 weeks
Hyperplasia and hypertrophy (increased cell size): 20-28 weeks
Hypertrophy dominates: 28-40 weeks
Why is last menstrual period unelaiable
Irregular length of periods; abnormal endometrial bleeding; the use of oral contraceptives; breastfeeding
Why is dating a pregnancy important
pregnancy being inappropriately identified as Large or Small for gestational age. Clinical decisions about delivery timings and methods (induction or Caesarean section) may not be correct; glucocorticoids are given prior to preterm delivery to enhance lung surfactant production and subsequent lung function.
Best way to date a pregnancy
Ultrasound
How does weed affect foetal growth
slow the fetal growth rate and can result in premature delivery. It can also lead to low birth weight, a shortened gestational period and complications in delivery.
How does heroin affect foetus
cause interrupted fetal development, stillbirths, and can lead to numerous birth defects. Heroin can also result in premature delivery, creates a higher risk of miscarriages, result in facial abnormalities and head size, and create gastrointestinal abnormalities in the fetus. There is an increased risk for SIDS, dysfunction in the central nervous system, and neurological dysfunctions including tremors, sleep problems, and seizures. The fetus is also put at a great risk for low birth weight and respiratory problems
How does cocaine affect foetus
Cocaine use results in a smaller brain, which results in learning disabilities for the fetus. Cocaine puts the fetus at a higher risk of being stillborn or premature. Cocaine use also results in low birthweight, damage to the central nervous system, and motor dysfunction.
How does alcohol affect foetus
CNS defects, mental retardation, facial abnormalities, major organ defects, miscarriage, Foetal Alcoholic Syndrome
How does smoking affect foetus
fetus is exposed to nicotine, tar, and carbon monoxide. Nicotine results in less blood flow to the fetus because it constricts the blood vessels. Carbon monoxide reduces the oxygen flow to the fetus. The reduction of blood and oxygen flow results in stillbirth, low birth weight, and ectopic pregnancy. There is an increase of risk of sudden death syndrome (SIDS) in infants.
How does gender affect birth weight
boys > Girls
How does 2nd pregnancy compare to first
second heavier
How does insulin affect foetus
Increase cell proliferation and nutrient availability
How does cortisol affect foetus
alter gene transcription, and cell differentiation
IGF 1 vs IGF 2
IGF 1 has little role in foetal growth is more dominated by 2
Role of prenatal glucocorticoids?
Tissue differentiation, lung surfactant, intestines (enzyme maturation), acts with thyroxine to mature lungs and nervous system
Name some other factors affecting growth
EGF, FGF, TGF, interleukin 1, embryonic cholinesterase
Define SGA
The infant has a birth weight <10th centile (also called ‘Small for dates’).
Define IUGR
Failure of the infant to achieve its predetermined (genetic) potential for a variety of reasons.
Define LBW
Less than 2,500g at delivery. Currently ~7% of live births (UK).
Define VLBW
Less than 1,500g at delivery. Currently ~1% of live births (UK).
Define ELBW
Less than 1,000g at delivery. Currently ~0.2% of live births (UK).
Why does birthweight matter
Infants who are inappropriately small at delivery are at increased risk of a range of neonatal complications.
What are short term effects of IUGR
Respiratory distress Intraventricular haemorrhage Sepsis Hypoglycaemia Necrotising enterocolitis Jaundice Electrolyte imbalance
What are medium term effects of IUGR
Respiratory problems
Developmental delay
Special needs schooling
What are long term effects of IUGR
Foetal programming
When is IUGR usually encountered
2nd and 3rd trimester
List maternal factors affecting IUGR
Chronic hypertension Connective tissue disease Severe chronic infection Diabetes mellitus Anaemia Uterine abnormalities Maternal malignancy Pre-eclampsia Thrombophilic defects
List some maternal behavioural factors affecting IUGR
Smoking Low booking weight (<50 kg) Poor nutrition Age <16 or >35 years at delivery Alcohol Drugs High altitude Social deprivation
List some foetal factors affecting IUGR
Multiple pregnancy Structural abnormality Chromosomal abnormalities Intrauterine (congenital) infection Inborn errors of metabolism
List some placental factors affecting IUGR
Impaired trophoblast invasion Partial abruption or infarction Chorioamnionitis Placental cysts Placenta praevia
Why does pre-ecclampsia cause IUGR
the main cause of pre-eclampsia is diminished remodelling of the spiral arteries by cytotrophoblast
which causes decreased blood flow and hence decreased nutrient supply to the placenta and fetus.
define pre-ecclampsia
gestational hypertension of at least 140/90 mmHg on two separate occasions ≥4 hours apart
Signs of pre-ecclampsia
proteinuria of at least 300 mg in a 24-hour collection of urine, arising de novo after the 20th week of gestation in a previously normotensive woman and resolving completely by the 6th postpartum week.
